The professional telephony boards definitely provide better quality than a normal voice modem.
The reason by telephony hardware pauses like that before dialing is because it is waiting to make sure there is a dial-tone before it makes the call. Most modems are set to wait a second or two to confirm that there is a working dial-tone and the call is ready to be placed. Some modems/boards let you change the time or remove the dial-tone check altogether with the driver's settings, for other devices it's a locked in feature that can't be disabled. Depending on the modem hardware, the modem may also dial the numbers slowly while other modems dial quickly with hardly any pause between numbers.
The pauses are actually there as a safety feature to try and improve the success rate of calls (i.e. checking for dial tone before placing a call, pausing between numbers so the other end has time to interpret them, dialing long tones so there is no doubt the other end would have received them, etc. etc.)